I’d like to gather some more information:

1. What version of Financial Navigator are you using? Please see the post What is the latest version of FN? for instructions on checking your version number.

2. Does this error occur when you try to open Financial Navigator, or does it occur during Transaction Entry?

3. If only during Transaction Entry, does it occur when trying to use another entity or the sample data?

4. Is this a recent error? Has this version of FN worked in the past?

5. Have you installed any other software prior to encountering this error?

It sounds like the problem was related to a corrupted library or program file. Re-installing FN is the best solution to replacing such files and getting FN to run again.